1. Field of the Invention
This invention relates to novel polyester compositions and to insulated electrical conductors, especially insulated wires for use as lead wires in refrigeration systems and other hermetically sealed electrical apparatus (often called "hermetic lead wires").
2. Introduction to the Invention
Many polyester compositions are known, including compositions which can be melt-shaped, e.g. melt-extruded around a conductor to provide an insulating coating. The physical and electrical properties of such polyester compositions are of course very important, and a great variety of polyester compositions have, therefore, been used or proposed for use, particularly as insulating coatings on wires. Reference may be made for example to U.S. Pat. Nos. 2,167,278, 3,671,487, 3,835,089, 4,048,128, 4,332,855, 4,767,668, 4,483,970 and 5,248,713, and to copending, commonly assigned U.S. patent application Ser. Nos. 08/275,174 filed Jul. 14, 1994 (MP1467-US2), 08/429,384 filed Apr. 26, 1995 (Docket No. MP1517-US1) and 08/435,339 filed May 4, 1995 (Docket No. MP1566-US1). The entire disclosure of each of said patents and patent applications is incorporated by reference herein for all purposes.
In conventional hermetic lead wires, the insulation is a wrapped polyester tape sandwiched between two polyester fiber braids. Such insulation is expensive and difficult to apply. U.S. Pat. No. 5,225,635 (Wake et al.), the disclosure of which is incorporated herein by reference, discloses a hermetic lead wire in which the insulation comprises an insulating layer made by melt-extruding a composition containing chlorosulfonated polyethylene, an acid acceptor, a filler, and a peroxide crosslinking agent.